One generation to next o genetic drift leads to

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one generation to next oGenetic drift leads to reduce genetic variation through loss of alleles Clicker Question: Which is true statement about genetic drift?GD is random and doesn't lead to adaptationExperimental StudyoFruit flies using genetic marker, the gene for leg-bristle morphology oTwo alleles; straight (wild type) leg bristles and forked (bent) bristles
Clicker Question: In this experiment, what can we conclude about genetic variation (GV) and genetic differences (GD)GV is decreased and GD are increased within populations
What circumstances lead to drift?
Clicker Question: What can we conclude about genetic variation and genetic differences?
Two major categories:1.Point mutationthat change a nucleotide base A.Often amino acid changing protein product B.Alter the rate of transcription, changing phenotype 2.Chromosomal MutationDifferent Methods for Mutation RatesoBiochemistry MethodRates of error and rates of DNA repair which used to estimate mutation per individual 130 mutations per generation oPhylogeny MethodPhylogenetic trees and estimate of time from branch points 160 mutations per generationoDirect MethodActually sequence DNA of parents and children
77 mutations per generation The Role of Mutations in Evolutionary Change oLTEE = Long term evolution experiment oWatched population change in lineages > 65,000 generations oAsexual populationwhere new forms occur by mutation oFrozen to store “genotype” representing a point in evolutionary sequence oBring back to life at later point oBacteria are haploid – actually called monoploidoAny mutation can be passed onoAra+ and Ara- (6 of each)oIf agar contains the sugar, Ara+ show white and Ara- shows red oRelative fitness of populations increased over time

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